Electrical power distribution systems often include overhead electrical power distribution lines mounted upon poles by a wide variety of mounting structure. Other distribution systems include underground distribution lines in which protected cables run under the ground surface. High voltage phasing meters are designed for use as safety tools by maintenance line workers to verify the status voltage and phase of the grid lines, phase angle between the lines and also phase sequencing. Even though feeder circuits in utility lines are intended to be well balanced in the initial deployment, one of the phases may turn out to be more heavily loaded than others. This leads to load imbalances.
Conventional high voltage phasing meters comprise high resistance reference and meter probes connected in series with a calibrated panel meter to read the voltage across the phase-to-phase or phase-to-ground terminals. They are designed for use as safety tools by high voltage line maintenance workers to verify the status of the line or equipment as nominal, induced or de-energized. Known devices for providing such measurements include contact type and non-contact cordless type. With contact type a reference probe or transmitter and a meter probe or receiver are connected in series with a cable as the loop is closed with load terminals. With the non-contact type each probe has a meter and the probes close the circuit through wireless means.
Presently, a variety of other phasing meters are being used. These include wireless phasing meters, GPS phasing tools and remote phase ID systems. A wireless phasing meter comprises a reference probe and a meter probe. Phase indication and readings are displayed in the meter housing. The operator has to use both of the probes on the lines and read the display while connected to the lines. There is no data storage facility and the display must be read instantaneously. Further, only trained personnel could interpret the phase sequence.
A GPS phasing tool consists of a meter probe, a field unit and a base unit. The base unit is installed at a remote location, such as a substation. The field unit consists of the meter probe with a signal processing system to compute the phase attributes of the power lines corresponding to the reference phase. This tool depends on the GPS base reference in the base station and uses a GPS receiver as a dedicated reference. The system depends on GSM/GPRS for phase sequencing. There is no facility for remote monitoring of phase sequence data.
A phase ID system has a field unit and a base unit. The field unit has a high voltage probe with a GPS receiver and a stable clock generator and wireless transceiver. A base unit consists of a GPS receiver and a send unit connected to a server. GPS timing systems are used to obtain snapshot phase measurements at an unknown field location and at a known reference location at the same instant of time. These two measurements are compared at the base station to determine the phase attribute at the unknown field location.
The disclosed system and method provides improvements over the known solutions discussed above.